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trane rtu model# YCD240B3HAJB

Hi, i was wondering if someone can shine some light on a problem im having with trane rtu unit.im new to hvac talk.model ycd240b3hajb. the induced motor is running continouasly even when t-stat is off.on a call for heat it goes throu the whole cycle and heat comes on.when it satisfies,or when u turn off heat on t-stat everything cycles off but the induced fan motor continues to run.im thinking its the ignition control board that needs to be replaced but want to confirm before i start replacing parts.could it also be the induced motor thats defective causeing it not to shut down?maybe internal switch is stuck closed in motor. any suggestions? thanks

There was a service bulletin on this that said the motor windings may fail internally and allow the motor to run without a call for heat.

What is the serial number sequence ?

Hey Rundawg, I have a job where i got 22 YCD300B4HAHB and have personally witnessed this problem. Before there was a bulletin on this, we had one unit catch on fire and we could not figure out what happened. It ended up that ALL the controls had to be replaced. It started with a bad inducer motor which shorted every control in the unit. The 460 volt transformer caught on fire. It was a mess.

It ended up after watching the other units run that the 2-speed inducer motor would short out what appeared to be between the windings of LO and HI speed. It would work fine in LO speed but when the 2nd stage of heat would come and energize the HI speed the motor would burn the windings. If you did not catch it in time the motor would short the winding and some how send line voltage back through the low voltage side (probably through the IGN Board) and fry EVERYTHING.

I think it is originally caused by a bad Run capacitor which in my case are 5 MFD / 440 Volt. And if left unnoticed the motor windings get hot when the run cap is less than 10% of it's rating.

As for the Bulletin I think Southern Mech is right that it may have expired. But this definitely must be fixed. There is a kit complete with all new wire harness, and an isolation contactor which will lock out HI/LO inducer speed or windings .

induced motor

Originally Posted by tech master

Hi, i was wondering if someone can shine some light on a problem im having with trane rtu unit.im new to hvac talk.model ycd240b3hajb. the induced motor is running continouasly even when t-stat is off.on a call for heat it goes throu the whole cycle and heat comes on.when it satisfies,or when u turn off heat on t-stat everything cycles off but the induced fan motor continues to run.im thinking its the ignition control board that needs to be replaced but want to confirm before i start replacing parts.could it also be the induced motor thats defective causeing it not to shut down?maybe internal switch is stuck closed in motor. any suggestions? thanks

hey alcomech,what do u think the problem is?the induced motor keeps running after t-stat is set on off.u think its the ignition board?thats what gives power to the motor?

hey alcomech,what do u think the problem is?the induced motor keeps running after t-stat is set on off.u think its the ignition board?thats what gives power to the motor?

No, bud. There are many issues with this its the inducer fan motor. I just replaced on last Friday, which would make about the 100th one. Easy test, pull the wires for high and low off the board, it still runs.

It's the inducer motor. First saw the problem got to be close to 8 years ago or so. Double check the relay on the ICB for burn marks, replace if necessary and don't forget to clean the burner screen. It should be plugged with cottonwood.

Officially, Down for the count

YOU HAVE TO GET OFF YOUR ASS TO GET ON YOUR FEET

I know enough to know, I don't know enoughLiberalism-Ideas so good they mandate them